hajj (n.)

also hadj, "the pilgrimage to Mecca," which every free Muslim is bound to make, as a religious duty, from Arabic hajj "pilgrimage," from hajja "he went on a pilgrimage." Related to Hebrew haghagh "he made a pilgrimage, celebrated a feast," hagh "a gathering." One who has made it is a hajji and afterward bears that title as a designation of honor.